Method of making borides



seamen". .ie, 1931 PATENT OFFICE ao'iaszo Ma'ruon. or MAKING-BORIDESClarcnocW. Balke, Highland Park, Ill.,v assignor to Ramct Corporation ofAmerica, North Chlcago, 111., a corporation of Illinois I a, Drawing.Application May es, mi

Serial No. 727,983.

Claims.

This invention relates to compositions having the hardness that isrequired for tools or .wear resisting, acid resisting, or abrasivematerials.

For so much of the subject matter disclosed 5 and claimed herein whichis also disclosed in my copending application, Serial No. 467,496, filed"May 29, 1930, which has matured into Patent 1,968,067, dated July 3,1984, I claim the priority of said application.

An object of the invention is the provision and production of a noveland an improved composition of boron with one or more hard refractorymetals from the group consisting of tantalum and columbium.

Another object of the invention is the provision and production of aboride of one or more hard refractory metals from the group consistingof tantalum and columbium.

Other objects of the invention will be apparent from the followingdescription.

The novel hard material of the invention com- Q prises-boron and one ormore refractory metals from the groupiponsisting of tantalum andcolumbium in suitable proportions to form a product including a borideor borides of refractory metal or metals and having certain propertiesdosirable for tools or wear resisting, acid resisting, or abrasivematerials. One such product has the boron and refractory metal or metalsin the proportion of, for example, from less than one atom to two atomsof boron to about one atom of the refractory metal or metals mentionedabove.

The proportions of from one to two atoms of boron to one atom of therefractory metal or 85 metals represent in atomic percentages from 50 to66.7 atomic per cent of boron to from 50 to 33.3 atomic per cent oftantalum and/or columbium. Expressed in percentages by weight, theforegoing formula gives from about 5.6% to 10.7% by 4 weight of boron tofrom 94.4% to 89.3% by weight of tantalum; and/or from about 10.4% to18.9% by weight of boron to from about 89.6% to 81.1% by weight ofcolumbium. The invention is not, however, limited to such 45 specificproportions but contemplates smaller percentages of boron which havebeen found to possess desirable properties. For example, 3% by weight ofboron to 97% by weight of the refractory metal or metals and 5% byweight of 50 boron to 95% by weight of the refractory metal or metalsresult in products having properties found useful and desirable in, forexample, tools, wear resisting and acid resisting materials.

In making the above described material, boron in the finely dividedstate is purified or dega siiied at about 1500 C. to volatilize anyorganic matter which may be contained therein and to ture of thepowders.

The fine powder mixture just described is placed in a crucible oftantalum sheet having a tight fitting cover. The closed tantalumcrucible 10 with the mixed powders therein is packed in tantalum powderin a graphite crucible, whereby to exclude oxygen, nitrogen, or otherembrittling gases from the powder mixture during the heating thereof. 15

After being packed in graphite, the loaded car- '1 bon crucible isheated preferably in a high frequency furnace. During this heattreatment the temperature in the furnace is slowly raised to about 2000C. and this temperature is maing0 tained for about one-half hour tocombine the boron with the proper amount of the tantalum and/orcolumbium to form a boride or borides thereof. When the carbon cruciblecontaining the powder mixture becomes red hot, 9. very 25 vigorousreaction takes place.

While'the product of the foregoing reaction is exceedingly hard and willreadily scratch many of the hard metal alloys now used for the formationof cutting tools, it is desirable to convert all, 30 or substantiallyall of the-boron into a boride. To this end that product is ground in aball mill for about twenty-four hours to a fine powder. The resultingfine powder may, if desired, be subjected to a forming pressuresufficient to hold the particles together during the evacuation of achamber or furnace into which the ground powder is next placed forheating. Whether or not the powder product is pressed, it is heated tofrom 1600 C. to 1700 C. in a vacuum to degasify it and to complete thereaction which converts substantially all of the boron into one or moreborides of tantalum and/or columbium.

Thus it will be seen that the' novel composition of the invention ismade by combining boron with one or more refractory metals from thegroup consistingof tantalum and columbium to form therewith a productincluding a boride or borides thereof and having the hardness and otherproperties desirable for tools or wear resisting, acid resisting, orabrasive materials.

While I have described a preferred embodiment of my invention, manymodifications may be made without departing from the spirit of theinvention, and I do not wish to be limited to the precise detailshereinbefore set forth, but desire to avail myself of all changes withinthe scope of the appended claims.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States, is:

1. A method of making borides which comprises grinding metal andpurified boron together, heating the finely divided mixture of boron andthe metal while excluding the embrittling gases therefrom to chemicallycombine said metal and boron, and degasifying the boride thus formed ina vacuum.

I 2. A method of making a boride of one or more metals from the groupcomprising tantalum and columbium which comprises heating a mixture ofboron and said one or more metals to unite the boron and said one ormore metals, and degasifying the mixture.

3. A method of making a boride of tantalum which comprises heating anintimate mixture of tantalum powder and boron to cause the tantalum toreact with the boron, and heating the mixture in a vacuum to completethe reaction.

4. A method of making-a. composition of boron and one or more'hardrefractory metals from the group consisting of tantalum and columbium,which comprises heating a mixture of said one or more hard refractorymetals and degasifled boron to about 2000 C. and reheating the productin vacuo.

5. Amethod of making a boride of one or more hard refractory metals'fromthe class including tantalum and columbium which comprises heating anintimate mixture of boron and a powder of said'one or more hardrefractory metals to cause the one or more hard refractory metals toreact with the boron, and heating the mixture in a vacuum to completethe reaction.

CLARENCE W. BALKE.

